Stent having helical elements

Abstract

An expandable stent comprised of a plurality of helical segments is disclosed. In one embodiment, the stent is generally cylindrical in shape having a cylindrical axis, and comprises a first and second set of helical segments. The helical segments in the first set are substantially parallel and have a first pitch forming a first helical angle with respect to the cylindrical axis. The helical segments in the second set are also generally parallel to each other and form a second pitch that differs from the first pitch, thereby forming a second helical angle with respect to the cylindrical axis. In an alternative embodiment, the stent comprises one set of helical segments and a plurality of circumferential elements that are joined together by the helical segments to form a plurality of cylindrical elements which are joined together to form a stent body. The stent may also have endzones.

1. An expandable stent comprising a main body, wherein, when the stent is unexpanded, the main body comprises:
 a plurality of expandable helical segments that comprise (a) expandable circumferential segments each having a single substantially S-shaped portion and (b) substantially H-shaped connecting segments; and 
 a plurality of main body cylindrical elements having collinear cylindrical axes, the main body cylindrical elements being adjacent to one another and being attached to one another by the connecting-segment portions of the helical segments, each main body cylindrical element having
 a circumference that is substantially identical to that of an adjacent cylindrical element and comprising 
 a plurality of circumferential segments joined together by the connecting-segment portions of the helical segments, thereby forming the cylindrical element, and the plurality of circumferential segments comprising a majority of the circumference of each cylindrical element. 
 
 
   
   
     2. The stent Of  claim 1 , wherein the circumferential segments are comprised of a plurality of segments joined together to form a repeating pattern. 
   
   
     3. The stent of  claim 1 , wherein the repeating pattern comprises a square wave form having curved peaks and valleys. 
   
   
     4. The stent of  claim 1 , further comprising: a first and second endzone, wherein the first and second endzones straddle the main body of the stent. 
   
   
     5. The stent of  claim 4 , further comprising a plurality of struts connecting each endzone to the main body. 
   
   
     6. The stent of  claim 5 , wherein the endzones are each comprised of a plurality of rings. 
   
   
     7. The stent of  claim 6 , wherein the rings in each endzone are joined together by a plurality of struts. 
   
   
     8. The stent of  claim 7 , wherein the rings are comprised of a plurality of alternating linear and curved segments. 
   
   
     9. The stent of  claim 8 , wherein the linear segments form an angle greater than 0° relative to the cylindrical axis of the cylindrical elements. 
   
   
     10. An expandable stent comprising:
 a first non-helical endzone; 
 a second non-helical endzone; 
 a generally cylindrically shaped main body having a cylindrical axis, the main body located between the first and second endzones and comprising:
 a plurality of adjacent cylindrical main body elements having cylindrical axes collinear with the main body cylindrical axis, the adjacent cylindrical main body elements connected together and comprising:
 a plurality of first expandable circumferential segments having a circumferential dimension; and 
 a plurality of second expandable circumferential segments having a circumferential dimension that is less than the first expandable segment circumferential dimension, each of the second expandable segments connected to two first expandable segments via substantially H-shaped connecting segments; and 
 wherein the cylindrical main body elements are joined by connecting together, via substantially H-shaped connecting segments, second expandable circumferential segments of adjacent cylindrical main body elements in helical patterns, thereby forming a plurality of generally parallel helixes in the main body. 
 
 
 
   
   
     11. The stent of  claim 10 , wherein at least a portion of the stent is radiopaque. 
   
   
     12. The stent of  claim 10 , wherein each of the endzones is attached to the main body with a plurality of struts. 
   
   
     13. The stent of  claim 10 , wherein the stent is manufactured from a contiguous piece of material. 
   
   
     14. The stent of  claim 10 , further comprising two helical segments in the main body, wherein the helical segments are 180° apart. 
   
   
     15. The stent of  claim 10  wherein each endzone comprises a ring formed from a plurality of contiguous segments. 
   
   
     16. The stent of  claim 15 , wherein the contiguous segments comprise linear and curved segments and wherein the linear and curved segments are joined together to form a repeating pattern. 
   
   
     17. The stent of  claim 16 , wherein the first expandable circumferential element comprises a plurality of linear and curved segments joined together to form a repeating pattern that resembles generally a square wave form having curved peaks and valleys. 
   
   
     18. The stent of  claim 17 , wherein the second expandable element comprises a plurality of linear and curved segments joined together and wherein the linear segments form an angle relative to the cylindrical axis of the stent that is approximately equal to the helical angle of at least one of the helixes in the main body. 
   
   
     19. An expandable stent that, when in an unexpanded state, comprises:
 a cylindrical axis, 
 a cylindrical main body about the cylindrical axis, the main body comprising: 
 a plurality of main body cylindrical elements having collinear cylindrical axes, the main body cylindrical elements being adjacent to one another and connected to one another by helical segments comprising expandable circumferential segments and substantially H-shaped connecting segments, 
 wherein the helical segments comprise 
 a plurality of first expandable helical segments having a first pitch and a plurality of second expandable helical segments having a second pitch that differs in value from the first pitch, and wherein the first helical segments cross the second helical segments and the first and second helical segments are attached to each other via substantially H-shaped connecting segments. 
 
   
   
     20. The stent of  claim 19 , wherein the second pitch has a value that is approximately twice that of the first pitch. 
   
   
     21. The stent of  claim 19 , further comprising a plurality of generally cylindrical shaped endzones having cylindrical axes that are collinear with the main body cylindrical axis. 
   
   
     22. The stent of  claim 21 , wherein the endzones have square outer edges. 
   
   
     23. The stent of  claim 20 , wherein the first helical segments are comprised of a plurality of circumferential segments joined together to form a helix. 
   
   
     24. The stent of  claim 23 , wherein the circumferential segments comprise a plurality of linear and curved segments joined together. 
   
   
     25. The stent of  claim 24 , wherein the linear segments lie at an angle between 0-45 degrees with respect to the cylindrical axis of the stent. 
   
   
     26. The stent of  claim 23 , wherein the second helical segments are comprised of a plurality of second circumferential elements joined together to form a second helix. 
   
   
     27. The stent of  claim 23 , wherein the stent is radiopaque. 
   
   
     28. An expandable stent comprising:
 a plurality of first expandable segments; 
 a plurality of second expandable segments; 
 a plurality of adjacent cylindrical main body elements having collinear cylindrical axes, the cylindrical main body elements formed by connecting first expandable segments with second expandable segments via substantially H-shaped connecting segments; 
 a plurality of first helical segments having a pitch, the first helical segments formed by connecting first expandable segments from adjacent cylindrical elements with each other; and 
 a plurality of second helical segments formed by connecting second expandable segments from adjacent cylindrical elements with each other, wherein the second helical segments have a pitch that differs from the pitch of the first helical segments. 
 
   
   
     29. The stent of  claim 28 , further comprising a first and second endzone, the first and second endzones straddling the main body. 
   
   
     30. The stent of  claim 28 , wherein at least one helical segment forms an angle of approximately 40° relative to the cylindrical axis of the stent. 
   
   
     31. The stent of  claim 1 , wherein each main body cylindrical element comprises:
 (1) a first plurality of the expandable circumferential segments and 
 (2) a second plurality of circumferential segments, wherein the first and second pluralities of circumferential segments are joined to each other by the connecting-segment portions of the helical segments, thereby forming the cylindrical element, and further wherein the first and second pluralities Of circumferential segments comprise a majority of the circumference of each cylindrical element. 
 
   
   
     32. The stent of  claim 31 , wherein the first circumferential segments alternate with the second circumferential segments. 
   
   
     33. The stent of  claim 31  or  32 , wherein the circumferential dimensions of the first and second pluralities of circumferential segments are equal. 
   
   
     34. The stent of  claim 31  or  32 , wherein the circumferential dimension(s) of one or more of the second plurality of circumferential segments is/are larger than the circumferential dimensions of the first plurality of circumferential segments.